Our two favorites are:
48° Northdestinations posts, but way better written (my pictures are better!) There's "Galley Essentials with Amanda", always an interesting cooking idea, tailored to the galley, not the trophy kitchen. News from the business of boat brokers, chandleries, and other marine-related business. New products. Well, just about everything you might want.
And if you are looking for a boat, the want ads in the back are a wonderful resource. In addition, 48° also catalogs all the boats offered by brokers, organized by length. So, if you are looking for a 27 footer, this is a great place to go to see a summary of what is available at the brokers docks. (But go to the docks! It's a wonderful day that is spent looking at boats! And the brokers want you there - really!).
48° also has a web presence.
Northwest is devoted pretty much (but not entirely) to power boats. But since few sailboats are truely sail-only boats, there is a lot of crossover. And both are boats, after all. Much of the gear featured applies equally well to both power and sail.
Northwest has a large want-ad section in the back, and also has an organized catalog of broker powerboats. Northwest Yachting also has a web presence.
I think if you are a power boater, Northwest Yachting is your magazine. If you are a sailor, then you will enjoy both magazines. We are very fortunate to have these two fine publications offered to us free every month. Go get a copy of each, and do some dreaming.